The present invention relates to a television conference system in which a promoter terminal that is used by a promoter who promotes a conference, and participant terminals that are used by participants in the conference are connected to one another via a communication line, a terminal for a television conference system, a connection control method for a television conference system, and a connection control program for a television conference system.
A multipoint connection television conference system in which a conference is performed among plural terminals that are remotely separated from one another is known. Particularly, a television conference system in which a server apparatus is not disposed (serverless), a public network is used, and data are transmitted and received among plural general-purpose personal computers (PCs) by the circuit switching method has advantages that the system can be easily configured, and that the cost can be reduced, and hence is preferably employed as a small-scale television conference system as disclosed in JP-A-5-22321.
Such a system is configured so as to be serverless. As the number of connected terminals is larger, therefore, the load of data processing to be performed in each terminal is more remarkably increased, so that parallel process cannot be performed by the processing power of a PC. As a result, a restriction that the number of bases which can join a conference, i.e., that of terminals which are connectable to the system cannot be increased without limitation is imposed on such a system.
FIG. 1 shows the configuration of a serverless television conference system. Referring to FIG. 1, five bases A to E are connected to each other in a one-to-one relationship. In the case where the base A serving as a transmission side is to transmit video and audio data produced by a camera 211 and a microphone 212 or conference data produced by a PC to the bases B, C, D, and E, for example, a transmission process must be performed four times. By contrast, in the bases B, C, D, and E serving as a reception side, the video, audio, and conference data must be received from the mutually connected base, and receiving and decoding processes must be performed four times in total. In this way, when a K number of bases are used in a conference, the data transmitting process must be performed (K−1) times, the data receiving process (K−1) times, and the process of decoding received data (K−1) times.
In the television conference system, when the amount of communication from one base to another base is 1, the total amount of communication in a conference is K×(K−1), or increased quadratically with the increase of the number of bases. When the number of bases is increased to a degree at which parallel process of reception, decode, and the like exceeds the throughput of the PC, there arises a problem in that, when all the bases are to be displayed on a monitor device of a terminal, for example, the display is delayed and simultaneity is impaired. Moreover, speech is enabled from all the connected terminals. When speech is made at the same time in plural bases, therefore, speeches are overlappingly output from loudspeakers of the terminals of the bases, thereby causing a problem in that it is difficult to identify the speakers.